CUS

Figure 4 shows the SEM image of CuS nanostructures at 150[degrees]C for 24 hrs at various magnifications.

The addition of CTAB plays an important role in the formation of CuS hexagonal plates-like structure [33].

In this case, the CUs have to wait, since no spectrum hole is available.

In the NSCRS, the PUs can obtain the half-duplex AF cooperation from the CUs and, then, a higher level of modulation and coding rate may be adopted to achieve a higher transmission rate; thus, the required time for transmitting the same amount of information from BS to the P[U.sub.M] can be reduced compared to that in the CCR; that is, it is reduced from [t.sub.M] in the CCR to [t.sub.M](1 - [[epsilon].sub.M]) in the NSCRS, and the remaining time of the P[U.sub.M], [t.sub.M][[epsilon].sub.M], is given to the CUs as an incentive time, where [[epsilon].sub.m] (0 [less than or equal to] [[epsilon].sub.m] < 1) is introduced as the proportion of incentive time in the reserved time for the mth PU in the CCR.

At last, we determine the optimal power allocation between the SN and the RN in each CU and the optimal power allocation between CUs.

This result is quite intuitive since in wireless networks, a larger number of CUs will cause more interference with each other.

We have divided the literature on CUs member group orientation/domination into theoretical and empirical groups of studies.

Disagreeing with Taylor (1971), Flannery (1974) used a simple graphical analytical model to show that non price rationing (i.e., restrictions on membership) is crucial for saver and borrower dominated CUs to operate.

CUs enjoy an exemption from paying federal income taxes (Walter, 2006).

The 2006 Governmental Accounting Office, GAO, report to Congress shows that CUs offered lower rates on loans and higher rates on deposits, when compared to banks, from 2000 to 2005.